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Re: [Qemu-devel] [PATCH 0/2] migration/channel errors and cancelling
From: |
Peter Xu |
Subject: |
Re: [Qemu-devel] [PATCH 0/2] migration/channel errors and cancelling |
Date: |
Tue, 19 Dec 2017 13:16:42 +0800 |
User-agent: |
Mutt/1.9.1 (2017-09-22) |
On Fri, Dec 15, 2017 at 05:16:53PM +0000, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <address@hidden>
>
> Hi,
> Where a channel fails asynchronously during connect, call
> back through the migration code so it can clean up.
> In particular this causes the transition of a 'cancelling' state
> to 'cancelled' in the case of:
>
> migrate -d tcp:deadhost:port
> <host tries to connect>
> migrate_cancel
>
> previously the status would get stuck in cancelling because
> the final cleanup didn't happen.
>
> This is the second part of the fix for:
> https://bugzilla.redhat.com/show_bug.cgi?id=1525899
IIUC this series tries to deliver the connection error a long way
until migrate_fd_connect() to handle it. But, haven't we already have
a function migrate_fd_error() to do that (which is faster, and
simpler)?
void migrate_fd_error(MigrationState *s, const Error *error)
{
trace_migrate_fd_error(error_get_pretty(error));
assert(s->to_dst_file == NULL);
migrate_set_state(&s->state, MIGRATION_STATUS_SETUP,
MIGRATION_STATUS_FAILED);
migrate_set_error(s, error);
notifier_list_notify(&migration_state_notifiers, s);
block_cleanup_parameters(s);
}
I think it's not handling the case when cancelling. If we let it to
handle the cancelling case well, would it be a simpler fix?
Moreover, I think this is another good example that migration is not
handling the cleanup "cleanly" in general... I really hope we can do
this better in 2.12. I'll see whether I can give it a shot, but in
all cases it'll be after the merging of existing patches since there
are already quite a lot of dangling patches.
Thanks,
--
Peter Xu